Masimo Corporation
MX ˙ BMV ˙ US5747951003
SecurityMX:MASI / Masimo Corporation
InstitutionRhumbline Advisers
Latest Disclosed Ownership129,619 shares
Latest Disclosed Value $ 23,055,262
Rhumbline Advisers reports 4.06% increase in ownership of MASI / Masimo Corporation

On May 12, 2026 - Rhumbline Advisers filed a 13F-HR form disclosing ownership of 129,619 shares of Masimo Corporation (MX:MASI) valued at $23,055,262 USD as of March 31, 2026. The entity filed a previous 13F-HR on February 13, 2026 disclosing 124,556 shares of Masimo Corporation. This represents a change in shares of 4.06% during the quarter.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-12 2026-03-31 13F MASIMO CORP COM COM 574795100 129,619 5,063 4.06 23,055 42.32 0.0197
2026-02-13 2025-12-31 13F MASIMO CORP COM COM 574795100 124,556 -2,052 -1.62 16,200 -13.28 0.0131
2025-11-06 2025-09-30 13F MASIMO CORP COM COM 574795100 126,608 -888 -0.70 18,681 -12.90 0.0150
2025-08-12 2025-06-30 13F MASIMO CORP COM COM 574795100 127,496 4,685 3.81 21,447 4.82 0.0184
2025-05-29 2025-03-31 13F/A-1 MASIMO CORP COM COM 574795100 122,811 -1,562 -1.26 20,460 -0.48 0.0191
2025-04-08 2025-03-31 13F MASIMO CORP COM COM 574795100 122,811 -1,562 20,460 0.0191
2025-05-29 2024-12-31 13F/A-1 MASIMO CORP COM COM 574795100 124,373 -2,641 -2.08 20,559 21.40 0.0184
2025-01-30 2024-12-31 13F MASIMO CORP COM COM 574795100 124,373 -2,641 20,559 0.0184
2024-11-12 2024-09-30 13F MASIMO CORP COM COM 574795100 127,014 -759 -0.59 16,935 5.24 0.0153
2024-08-01 2024-06-30 13F MASIMO CORP COM COM 574795100 127,773 -5,359 -4.03 16,092 -17.69 0.0151
2024-05-09 2024-03-31 13F MASIMO CORP COM COM 574795100 133,132 -4,819 -3.49 19,550 20.91 0.0188
2024-02-08 2023-12-31 13F MASIMO CORP COM COM 574795100 137,951 -4,578 -3.21 16,169 29.39 0.0169
2023-11-09 2023-09-30 13F MASIMO CORP COM COM 574795100 142,529 -16,455 -10.35 12,497 -52.23 0.0145
2023-08-08 2023-06-30 13F MASIMO CORP COM COM 574795100 158,984 9,627 6.45 26,161 96,788.89 0.0293
2023-05-11 2023-03-31 13F MASIMO CORP COM COM 574795100 149,357 2,366 1.61 28 -99.88 0.0340
2023-02-14 2022-12-31 13F MASIMO CORP COM COM 574795100 146,991 6,206 4.41 21,747 9.43 0.0292
2022-11-10 2022-09-30 13F MASIMO CORP COM COM 574795100 140,785 -2,998 -2.09 19,873 5.77 0.0296
2022-08-11 2022-06-30 13F MASIMO CORP COM COM 574795100 143,783 7,802 5.74 18,788 -5.07 0.0274
2022-05-12 2022-03-31 13F MASIMO CORP COM COM 574795100 135,981 879 0.65 19,791 -49.97 0.0255
2022-02-10 2021-12-31 13F MASIMO CORP COM COM 574795100 135,102 2,476 1.87 39,555 10.17 0.0485
2021-11-12 2021-09-30 13F MASIMO CORP COM COM 574795100 132,626 -2,417 -1.79 35,903 9.66 0.0486
2021-08-05 2021-06-30 13F MASIMO CORP COM COM 574795100 135,043 1,185 0.89 32,741 6.50 0.0430
2021-05-06 2021-03-31 13F MASIMO CORP COM COM 574795100 133,858 -3,896 -2.83 30,742 -16.85 0.0418
2021-02-10 2020-12-31 13F MASIMO CORP COM COM 574795100 137,754 -3,449 -2.44 36,970 10.91 0.0510
2020-11-12 2020-09-30 13F MASIMO CORP COM COM 574795100 141,203 -4,187 -2.88 33,332 0.56 0.0522
2020-08-13 2020-06-30 13F MASIMO CORP COM COM 574795100 145,390 14,737 11.28 33,147 43.24 0.0554
2020-05-06 2020-03-31 13F MASIMO CORP COM COM 574795100 130,653 -1,019 -0.77 23,141 11.19 0.0485
2020-02-05 2019-12-31 13F MASIMO CORP COM COM 574795100 131,672 -991 -0.75 20,812 5.44 0.0348
2019-10-23 2019-09-30 13F MASIMO CORP COM COM 574795100 132,663 -2,175 -1.61 19,739 -1.63 0.0361
2019-08-14 2019-06-30 13F MASIMO CORP COM COM 574795100 134,838 1,594 1.20 20,067 8.91 0.0377
2019-05-01 2019-03-31 13F MASIMO CORP COM COM 574795100 133,244 1,744 1.33 18,425 30.50 0.0357
2019-01-31 2018-12-31 13F MASIMO CORP COM COM 574795100 131,500 36,927 39.05 14,119 19.88 0.0307
2018-11-07 2018-09-30 13F MASIMO CORP COM COM 574795100 94,573 -1,940 -2.01 11,778 24.98 0.0227
2018-08-06 2018-06-30 13F MASIMO CORP COM COM 574795100 96,513 4,554 4.95 9,424 16.52 0.0190
2018-05-02 2018-03-31 13F MASIMO CORP COM COM 574795100 91,959 -6,693 -6.78 8,088 -3.32 0.0169
2018-02-09 2017-12-31 13F MASIMO CORP COM COM 574795100 98,652 -8,878 -8.26 8,366 -10.12 0.0170
2017-11-06 2017-09-30 13F MASIMO CORP COM COM 574795100 107,530 16,953 18.72 9,308 12.70 0.0202
2017-08-02 2017-06-30 13F MASIMO CORP COM COM 574795100 90,577 2,919 3.33 8,259 1.03 0.0189
2017-05-02 2017-03-31 13F MASIMO CORP COM COM 574795100 87,658 27,015 44.55 8,175 100.02 0.0191
2017-01-27 2016-12-31 13F MASIMO CORP COM COM 574795100 60,643 1,588 2.69 4,087 16.34 0.0104
2016-11-08 2016-09-30 13F MASIMO CORP COM COM 574795100 59,055 3,492 6.28 3,513 20.39 0.0097
2016-08-11 2016-06-30 13F MASIMO CORP COM COM 574795100 55,563 -180 -0.32 2,918 25.13 0.0086
2016-05-02 2016-03-31 13F MASIMO CORPORATION COMMON STOC COM 574795100 55,743 1,050 1.92 2,332 2.73 0.0072
2016-02-03 2015-12-31 13F MASIMO CORPORATION COMMON STOC COM 574795100 54,693 3,845 7.56 2,270 15.76 0.0073
2015-11-04 2015-09-30 13F MASIMO CORPORATION COMMON STOC COM 574795100 50,848 1,277 2.58 1,961 2.14 0.0067
2015-08-04 2015-06-30 13F MASIMO CORPORATION COMMON STOC COM 574795100 49,571 -3,500 -6.59 1,920 9.71 0.0061
2015-05-12 2015-03-31 13F MASIMO CORPORATION COMMON STOC COM 574795100 53,071 4,375 8.98 1,750 36.40 0.0050
2015-02-06 2014-12-31 13F MASIMO CORPORATION COMMON STOC COM 574795100 48,696 -4,730 -8.85 1,283 12.84 0.0037
2014-11-12 2014-09-30 13F MASIMO CORPORATION COMMON STOC COM 574795100 53,426 -1,290 -2.36 1,137 -11.93 0.0034
2014-08-06 2014-06-30 13F MASIMO CORPORATION COMMON STOC COM 574795100 54,716 -32,965 -37.60 1,291 -46.10 0.0038
2014-05-06 2014-03-31 13F MASIMO CORPORATION COMMON STOC COM 574795100 87,681 -1,850 -2.07 2,395 -8.48 0.0071
2014-02-03 2013-12-31 13F MASIMO CORPORATION COMMON STOC COM 574795100 89,531 1,585 1.80 2,617 11.69 0.0077
2013-11-05 2013-09-30 13F MASIMO CORPORATION COMMON STOC COM 574795100 87,946 254 0.29 2,343 26.04 0.0073
2013-08-07 2013-06-30 13F MASIMO CORPORATION COMMON STOC COM 574795100 87,692 87,692 1,859 0.0060
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.